1. Field of the Invention
The present invention relates to techniques of realizing low power consumption and returning the power supply level of an electronic appliance that has a plurality of hardware interfaces mounted thereon for communicating with another electronic appliance. Moreover, the electronic appliance is not restricted to a particular filed, for which any types of appliances are targeted.
The proposed invention includes an electronic appliance, a method of setting a return interface, a return communication method and a computer program.
2. Description of the Related Art
In recent years, increasing concerns are energy issues and environment issues. With these concerns as a backdrop, it is demanded to further reduce the power consumption of electronic appliances used in daily life. On this account, many electronic appliances have a low power consumption operation mode in which a nonuse state after a power source is turned on is detected to automatically stop power supply to unnecessary circuits.
For example, in an image forming apparatus such as a printing apparatus and a FAX machine, the state in which no input signals are detected is continued for a certain time period or longer, and then the operation mode is automatically shifted to the low power consumption mode. In the low power consumption mode, the image forming apparatus is controlled to turn off power supply to unnecessary circuits except circuits used for communication with external devices. In addition, in the case in which a return signal or image data is received from an external device, power supply is restarted to individual circuits. Thus, the image forming apparatus is ready to form images.
However, with the advance of digital imaging technology, electronic appliances are demanded to cope with various communication forms and communication standards. On this account, electronic appliances nowadays have a plurality of hardware interfaces mounted therein for communication with external devices.
The return from the low power consumption mode to the normal operation mode is sometimes given from an external device as a return signal.
Thus, even during the low power consumption mode, many electronic appliances adopt a scheme to continue power supply to a hardware interface used for communication with external devices. FIG. 1 shows a form of power supply in the low power consumption mode.
In addition, FIG. 1 shows the case in which an electronic appliance is a printing apparatus. In the case of the printing apparatus 1 shown in FIG. 1, circuit blocks that are turned on in the low power consumption mode are depicted white. Moreover, circuit blocks that are turned off in the low power consumption mode are shaded.
However, electric power is supplied to a large number of hardware interfaces, which causes a problem that it is difficult to enjoy the advantage of the low power consumption mode at the maximum. In other words, there is a problem that goes against the trend of low power consumption to set back an efficient reduction in power consumption.
Furthermore, JP-A-2005-196741 (Patent Reference 1; Paragraph Number 0018) proposes a scheme in which power supply during the low power consumption mode is restricted to the circuits of a reception system for a hardware interface used for communication with an external devices. In other words, a scheme is proposed in which a transmitting function is controlled to turn off during the low power consumption mode. With this scheme, it is intended to more reduce power consumption than techniques before.